1. Field of the Invention
The present invention relates to a portable cellular phone and more particularly to the portable cellular phone being capable of mounting a UIM (User Identity Module) card and being capable of reducing a number of times user data is read or written from or to the UIM card.
The present application claims priority of Japanese Patent Application No. 2002-112606 filed on Apr. 15, 2002, which is hereby incorporated by reference.
2. Description of the Related Art
In a third generation portable cellular phone employing a W-CDMA (Wideband-Coded Division Multiple Access) method, a user ID (IDentification number) is incorporated in an IC (Integrated Circuit) card having a size of a postage stamp, as called a “UIM card”. The UIM card, by mounting, in addition to a processor to perform an authentication process or a like, a flash memory serving as a storage unit, can store user data. Moreover, the UIM, card, since it can be detached from the third generation portable cellular phone proper, can be interchanged and used between the third generation portable cellular phone proper and another third generation portable cellular phone proper. Therefore, it is made possible for the same user to use a plurality of third generation portable cellular phones using the same UIM card and the same third generation portable cellular phone can be used around among a plurality of users by replacing different UIM cards. For example, in a pre-third generation portable cellular phone portable cellular phone being an earlier model, data such as an address book that has to be prepared every time a user buys a new portable cellular phone, is written in an embedded memory and, as a result, unless a personal computer installing “telephone number directory” software for a portable cellular phone is used, it is difficult for the user to transfer such data by himself from the pre-third generation portable cellular phone portable cellular phone to another pre-third generation portable cellular phone portable cellular phone, that is, to port data between pre-third generation portable cellular phone portable cellular phones. However, the third generation portable cellular phone has an advantage in that it can store such as an address book in the UIM card and therefore a further inputting operation is not required when the user buys a new third generation portable cellular phone.
In the third generation portable cellular phone that can use the UIM card, after the UIM card is inserted into the third generation portable cellular phone proper, for example, by being replaced with another UIM card, user data being stored in the UIM card, when the third generation portable cellular phone is turned ON, is expanded (that is, stored) in an internal RAM (Random Access Memory) come with in the portable cellular phone. Then, when the user refers to a telephone number directory (record) or a like, user data being expanded in the internal RAM is read.
Generally, since space for mounting the UIM card is located in a battery pack area, to detach and attach the UIM card, a battery pack has to be first removed. Therefor, a judgement as to whether the UIM card has been replaced or not is made by detecting whether the battery pack has been removed or not.
However, in the conventional third generation portable cellular phone, a judgment as to whether or not the UIM card has been detached is made by detecting whether the battery pack has been removed or not and, therefore, if the battery pack has been removed once, irrespective of whether the UIM card has been actually removed or not, user data is read from the UIM card all the time and the data is expanded in the internal RAM when the portable cellular phone is turned ON another time. Since reading user data from the UIM card requires time of about several tens seconds in many cases, though the required time varies depending on a data storing capacity, the user feels that the portable cellular phone expends much waiting time. However, expansion of user data into the internal RAM from the UIM card occurring every time the third generation portable cellular phone is turned ON so long as the UIM card has not been replaced is not necessary and, if it can be judged and confirmed that no UIM card has been detached when the third generation portable cellular phone is turned ON, neither the reading nor the expanding are necessary. It is desirable that a number of times data is read from the UIM card is as small as possible.